const fp = require('lodash/fp');
const cars = [{
    name: 'Ferrari FF',
    horsepower: 660,
    dollar_value: 700000,
    in_stock: true
  },
  {
    name: 'Spyker C12 Zagato',
    horsepower: 650,
    dollar_value: 648000,
    in_stock: false
  },
  {
    name: 'Jaguar XKR-S',
    horsepower: 550,
    dollar_value: 132000,
    in_stock: false
  },
  {
    name: 'Audi R8',
    horsepower: 525,
    dollar_value: 114200,
    in_stock: false
  },
  {
    name: 'Aston Martin One-77',
    horsepower: 750,
    dollar_value: 1850000,
    in_stock: true
  },
  {
    name: 'Paaani Huavra',
    horsepower: 700,
    dollar_value: 1300000,
    in_stock: false
  }
];

//练习1
let isLastInStock = fp.flowRight(fp.prop('in_stock'), fp.last); 
console.log('---练习1---', isLastInStock(cars));

//练习2
let getFirstCarName = fp.flowRight(fp.prop('name'), fp.first); 
console.log('---练习2---', getFirstCarName(cars));

//练习3
let _average = function (xs) {
  return fp.reduce(fp.add, 0, xs) / xs.length;
}
let averageDollarValue = fp.flowRight(_average, fp.map("dollar_value"));
console.log('---练习3---', averageDollarValue(cars));

//练习4
let _underscore = fp.replace(/\W+/g,'_');
let sanitizeNames = fp.flowRight(fp.toLower, _underscore);
console.log('---练习4---',sanitizeNames(["Hello World"]));
